This invention relates to 3-D model making employing photo-cured liquid polymers and, more particularly, to apparatus for curing a photocurable liquid polymer to create a 3-dimensional model comprising, a container containing the photocurable liquid polymer; a substrate upon which to build the model disposed in the container and in the polymer; a knife member disposed over the substrate with a bottom edge parallel to the substrate; movement means for moving the bottom edge of the knife member up and down with respect to the substrate and for moving the knife member over the substrate parallel thereto; curing means for creating and conducting a 1-dimensional pattern of light beams for curing the liquid polymer to a line immediately behind and parallel to the bottom edge and therefrom into the liquid polymer; and, control means connected to the movement means for repeatedly moving the knife member over the substrate parallel thereto in a series of adjacent layers and connected to the curing means for simultaneously creating and conducting a series of 1-dimensional patterns of light beams into the liquid polymer to cure the liquid polymer in a line-by-line and layer-by-layer pattern from a bottom layer to a top layer.
It is known in the art that 3-dimensional parts can be constructed by photocuring a liquid polymer in a controlled fashion. Typically, the control is accomplished by a computer. In such instances, the model-making device can be treated and considered in the manner of other computer peripheral devices. This is particularly true and applicable where the specifications for the model to be "built" are generated by a computer-resident CAD system, or the like.
One prior approach to such model making can be found in the patent of Swainson (U.S. Pat. No. 4,041,476) which is also depicted in greatly simplified form in FIG. 1. The figure or model 10 is created in-situ within the liquid polymer 12 by the controlled intersection of two laser beams 14 from laser sources 16. Each laser beam 14 has insufficient energy to cure the photo-curable liquid polymer 12; but, the intersection of the two beams creates sufficient energy to cause curing thereof. Thus, by moving the intersection of the two laser beams 14 in a controlled manner through the liquid polymer 12, the model 10 can be built up point by point. As can be appreciated, however, it is hard to accurately control the intersection point due to factors such as refraction and varying distances travelled within the polymer 12.
A second approach is disclosed in two different embodiments in the two patents of Fudim (U.S. Pat. Nos. 4,752,498 and 4,801,477) which are also the subject of the simplified drawings of FIGS. 2 and 3, respectively. In Fudim's '498 approach of FIG. 2, the liquid polymer 12 is contained within a tank 18. A substrate 20 upon which the model is to be constructed is disposed in the bottom of the tank 18 and parallel to the top surface 22 of the polymer 12. A flat exposure member 24 is disposed above the substrate 20 and parallel thereto. The bottom portions 26, 28 of the exposure member 24 are transparent to the passage of photocuring light. Moreover, the lower bottom portion 28 is placed below the top surface 22 of the polymer 12 at a precise and known distance "d" from the substrate 20. The top layer of the member 24 is an exposure mask 30. A curing light source 32 of light beams 34 is disposed over the exposure mask 30. It was Fudim's intent that by changing the light-passing qualities of the mask 30, the passage of the light beams 34 therethrough could be controlled more readily than in the case of the prior art approach of FIG. 1 and, therefore, accurate models could be created.
As those skilled in the art will undoubtedly recognize, the approach of Fudim's '498 patent did fix the distance from the top of the polymer 12 to the substrate 20; but, the distance the light beams 34 travel changes as the model builds up from the bottom. Moreover, the creation of complex shapes is virtually impossible using such an approach unless a very complex mask-changing and control technique is employed. Apparently, Fudim also recognized the shortcomings of his first approach and modified it to create the apparatus and method of his '477 patent, which is shown in simplified form in FIG. 3. In this approach, the exposure member 24' and the curing light source 32' are connected together for horizontal and vertical movement by the controller 35 while the exposure mask is controlled by its own controller 33. The exposure member 24' and the curing light source 32' are also reduced in their overall horizontal dimensions and the lower bottom portion 28 is spaced well below the exposure mask 30 so as to be initially positionable just above the substrate 20. The exposure mask 30 in this embodiment is a dynamically changeable device such as a 2-dimensional liquid crystal display panel. To cure the polymer 12 and create the model, the light source 32' and exposure member 24' are moved over the surface of the substrate 20 from area to area. At each area, the exposure mask 30 is set for that portion and layer of the model being created and the light source 32' employed to cure a layer of the polymer 12. When each area of the model for one layer has been cured and created, the light source 32' and exposure member 24' are raised to the next level and the process is repeated. This whole area-by-area and layer-by-layer process is repeated until the whole model has been built.
While Fudim's '477 approach is undoubtedly better than his '498 approach and more likely to produce a useful output, those skilled in the art will readily recognize and appreciate that it is still an approach which is best left at the laboratory curiosity stage and not one upon which large-scale commercial apparatus can be based. For one, the process would be much too slow. For another, the components required would be much too complex and expensive to create in a low-cost commercial product.
Another prior art approach as employed in apparatus of a company known as 3D Systems is depicted in FIG. 4. In this case, a previously-cured base element 37 onto which additional layers are to be molded is "overdipped"; that is, the base element 37 is dipped into the uncured liquid polymer 12 to the ghosted position 37' and then brought back up to a point at which the top layer of the uncured polymer 12 is at approximately (but slightly thicker than) the desired thickness. Then, a squeegee or blade 36 is drawn across the top layer of the uncured polymer 12 to level it to the desired thickness prior to a laser beam 38 being used to irradiate and cure the layer.
Still another approach which is substantially identical in function to the above-describe approach is depicted in FIG. 5. In this DuPont approach, the previously-cured base element 37 is lowered into the liquid polymer 12 directly to approximately the desired depth. A first blade 40 is then dipped into the top of the polymer 12 and withdrawn to a point just above the top of the liquid polymer 12. Then, the first blade 40 is drawn across the top surface of the polymer 12 over the base element 37 which causes the polymer 12 which has clung to the first blade 40 to fill any pockets or voids at the top of the solution. A second blade 42 positioned behind the first blade 40 at about the top of the polymer 12 is moved across the polymer 12 in the manner of the above-described embodiment and again followed by laser irradiation.
Wherefore, it is an object of the present invention to provide a method and apparatus for the creation of 3-dimensional parts by photocuring a liquid polymer in a controlled fashion which is fast in operation.
It is another object of the present invention to provide a method and apparatus for the creation of 3-dimensional parts by photocuring a liquid polymer in a controlled fashion which employs simple components which can be produced at low cost for commercial sales.
It is still another object of the present invention to provide a method and apparatus for the creation of 3-dimensional parts by photocuring a liquid polymer in a controlled fashion which can be used to produce models with high accuracy and complex shapes.
Other objects and benefits of the present invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.